----- Original Message ----
From: Bruce Griffiths <[EMAIL PROTECTED]>
To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
Sent: Thursday, May 22, 2008 5:09:32 PM
Subject: Re: [time-nuts] Comparing Reference Accuracy
Stanley Reynolds wrote:
> The prams for sample size could also be set in the sampling PICs you would
> probably want to set them all the same.
>
A much better scheme is to time stamp the leading edges of the various
PPS signals (from the GPS receiver and the divided down output of each
GPSDO) using a common time base.
The time stamp resolution is improved by using a higher frequency clock
and/or a time interval interpolator for each input channel.
This is the scheme used by NIST for remote frequency measurement.
Bruce
Getting back to the idea that the DO controller needs to measure the oscillator
to make corrections, would your suggestions make a better DO controller if used
in this measurement ? Or maybe instead of just measuring the difference
between a group of DOs, we generate a improved standard from the group
canceling their unique errors. This would force us back to real time so post
processing would be out.
I do understand that we need a better ruler to determine how good our ruler is,
but at some point we improve to a group that is at the same level
by elimination of the out-lye-rs. Or in my case the limit that I'm capable of
implementing at this point.
Stanley
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